┌ CLASSES. ┌ ORDERS. ┌ GENERA. │ │ │1st. Extensive Opposition, │ │ │ Circumduction and │ │ │ Rotation. │ │1st. With │2d. Extensive Opposition │ │ Contiguous │ and Circumduction. │1st. Moveable. │ Surfaces. │3d. Limited Opposition. │ │ │4th. Rotation. │ │ └5th. Sliding. ARTICULATIONS. │ │2d. With Continuous │ └ Surfaces. │ │ ┌1st. With Surfaces │ │ in juxta-position. │ │2d. With Surfaces │ │ inserted └2d. Immoveable. │ into each other. │3d. With Surfaces └ implanted. After having thus divided the articulations, let us offer upon each class some general observations. But let us first remark that the preceding table, considered in respect to the moveable articulations with contiguous surfaces, indicates perfectly the disposition of these articulations as to luxations, which are so much the more frequent as the motions are more extensive. The first genus is the most exposed to it, the last the least so; and the others are more or less so according to their distance from the first. II. _Observations upon the Moveable Articulations._ The class of moveable articulations is the most important to be considered, because their mechanism is the most complicated of the two orders composing this class, as we have seen. The latter, or that of the articulations with continuous surfaces, will not be considered in our general observations, as it embraces only one species of motion, that of the vertebræ, this motion will be noticed in the examination of the spine. The order of the moveable articulations with contiguous surfaces, comprises, as we have said, five genera characterized by their respective motions. _First Genus._ Extensive opposition, circumduction and rotation characterize this genus. The first by the extent and number of its motions. The articulations of the humerus with the scapula and the femur with the ilium are examples of it; they even exclusively compose it.